Drain pipe not under the screed

I also think that the connection was simply forgotten and added later. Either way. Maybe because the plumber did not have a kitchen plan?
Be that as it may: check the kitchen plan/floor plan to see if you still have 10cm of leeway. Then just move the base cabinets 10cm away from the installation/wall and have a deeper countertop installed. Discuss the additional cost with the GU and come to an agreement.

Wow, so many replies! I’ve been on the move a lot!

The installer was here at the beginning of May. I really don’t understand why the drain pipe goes so far to the right through the floor slab...

He’s coming again on Wednesday because he needs to move something in the utility room, maybe we’ll meet him and then we’ll ask about it.

Regarding the bathroom and underfloor heating, I once started a nice thread here. That seemed to fit pretty well. (here’s an updated picture of the shower again)

What kind of masonry is that? I would now guess that the sand-lime brick shell is simply not thick enough to allow slots of this size. And presumably, the height in the floor construction was not sufficient to bring the pipe under the screed. You don't just have to install the pipe, but at the same time also ensure a slope and somehow make the bend to the drain pipe. I personally don't find it bad at all if the sink cabinet is going there anyway. I would rather question what kind of blue foil is on the dwarf wall (photo shower). Such PE foils as vapor barriers are actually no longer used today because they are too tight. A small mistake during installation and you already have moisture in the construction, which, thanks to this foil, can hardly dry out again.

So after consulting with the general contractor, we are not much wiser either. Since they didn't have a kitchen plan, they probably just put the pipe "somewhere," meaning where the sink of the "sample installation" was drawn.
The screed is currently being heated with underfloor heating. I noticed two things where I would like to hear your opinion.
1) Is it normal that your expansion joints are not continuous and have a kind of predetermined breaking point?
2) The corners are not very even, is it then our responsibility (EL tile laying) to sand them down?

To1) I already told you that your trades are not working cleanly enough. I see the expansion joint as less problematic than the corners where the cement screed was installed poorly. Do you want to lay the tiles yourself? If yes, why do you ask such questions?

To2) If you did not commission it, then the screed grinding is your task. But that is only 2 hours with the disc grinder.

Yes, we will tile everything ourselves except for the bathrooms.
So "nice screed" is tile setter work?
Or is there a standard that it must be clean and level?

That we will, for example, prime it with Tiefengrund is clear.